Concentrator



G. A. OVERSTHOM.

CONCENTRATOR.

APPLlcATmN HLED/ Nov. 2o. 1916.

Patented May 30,1922;

' fnuenon MAW GUSTAVE A. OVERSTROM; OF PASADENA, CALIFORNIA.

Y UONCENTRATOR.

nemesi.

Specication of Letters Patent.

Patented May 30, i922.

Application filed November 20,1916. ,Serial No. 132,387.

To all w hom it may concern:

Be it known that I, GUsTAvE A. OVER- s'rnoM, a citizen of the UnitedStates, resid ing at Pasadena, county of Los Angeles, State ofCaliforniahave invented a new and useful Concentrator, of which thefollowing is a specification.

This invention relates to those types of concentrators in which areciprocating motion keeps the material moving, while a low of waterforwet Work, or gravity and skim-l ming` rililes for dry work,accomplishes the separation while the material is in motion.

The main object of the invention is to provide a greatly simplifiedconstruction, adaptable to handle a'vvide range ofv sizes and so simplethat the most unskilled laborer can understand it.

Another object is to make a grit and sand proof head motion, eliminatingthe use of slides, toggles, rockers, eccentrics, cams, etc., and all butone bearing, therebyv eliminating repairs.

A further object is to provide, without impairing theeffectiveness, alconstruction so cheap to build'that machines of this class may reach theman of limited means, and of such nature that repairs can be made in anyout ol theway mining camp.

Alnother object is to produce a concentrator automatically operating ata constant speed, although there may be a variation in the speed of themotive power.

A still further object is to construct and oporatea concentratorstructure on the pendulum principle, thereby reducing strains to aminimum, consequently prolonging the lil'c of the structure, andrequiring the least possible power to operate. l

.l further object is to provide a simple tilting adjustment between theshaking frame and the table top. and to concentrate the tilting. strokeand water adjustments at one point. therebymaking it possible for a manto attend to more tables than he otherwise could do.

Other objects and advantages of my invention will appear hereinafter.

ln the drawings I have soown well known type of coneentrator, known as atransversely inclined concentrating table with diagonally endingriftles.

Referring thereto, Figure l is a plan view.

Figure 2 is a vertical, longitudinal section through the center of thestructure, plainlyl illust-rating thebuling means and the tiltingadjustment.

Figure 3 is a vertical, longitudinal section through the table top,taken near the lower side of the table, showing the full view of thefloor and shaking frame and the means for hinging the table top -to theshaking frame.

Figure 4 is a cross-sectional elevation, taken about half way from theend of the table.

Figure 5 is an end elevation, looking at the discharge end of the table.

The invention comprises a frame adapted to move in a substantiallyhorizontal direction, an unbalanced revolving weight attached to theframe and adapted to impart movement thereto, means for producing aconstant speed differential `reciprocatlng movement therefrom, andv aconcentrating sur-face adjustably attached to the shaking frame.

It is desirable, but not absolutely necessary, that the concentratorstructure be so supported that naturally it will'oscillate or beat timeat the rate which, by experience, has been found to give the bestseparating results; hence the center of gravity of the reciprocatingpart of the Structure is of 1 such a distance from the point of fulcrum,or bending, and so supported that a pendulum is produced, which, whengiven a slight assistance, will oscillate at the desired number ofstrokes per minute. As a consequence the strains set up in thereciprocating structure and the power required to move it are reduced toa minimum.Y It follows naturally that it is best to apply thepowergiving the impulses at the same rate as the pendulunr time. lt isalso desirable, but not necessary, to naturally limit the pendulummovement to a length nearly corresponding to the average length ofstroke which by practice has been found to give best results; hence theoscillating structure is supported b v springs of a stiffness suitableto give the desired length of movement` thereby produc,-v ing a cvwloidal pendulum. lt is a well known law that the time of a pendulum isindependent of the length `of oscillation; hence if by suitable meansthe length of oscillation is varied, the time will remain the same.

This feature is important, as the time or rate of speed in aconcentrating mill is the tot only element entering into the lseparatingproblem, which is not supposed to vary considerably. To take care ofother varying elements,-adjustments (such as amount of water, incline,length and nature of stroke) must be provided.

When at times, as unavoidably will happen, the speed of the motive powerwill vary, the separating work done by the usual concentrator becomesvery indifferent and poor. In accordance with the principles of myinvention this undesirable result is avoided as will be more fullyhereinafter explained.

In the concentrator here described .the time of oscillation tries toremain uniformly the same, and actually does so within fairly largelimits ofincrease or decrease in the v speed of the motivepower,.providing the sol belt, connecting the motive power to therevolving unbalanced weight, is small and loose enough to slip to someextent. On account of the power required to operate this table beingvery slight, the unbalanced revolving weight is small and the belt isunusually small and loose as compared to other tables doing similarwork; hence when increase inthe speed of the motive power does occur,the belt slips slightly and the table operates at its natural uniformspeed in spite of the increase in power.

In the drawings I have shown a transversely'inclined concentrating tableof well knownoutline, and referring to the drawings in detail: The tabletop (l) may be of any suitable construction; I have shown it with theusual linoleum surfacev and riflles.

The top (1) is tiltingly attached from cross beams (2) of table top (l)to the movable frame (3) by'means of hinge bolts (4)' pass'- ing throughthe beams (2) and a hinge membei` (5), (which in this case for conAvenience is an extension of a'member of a different function), attachedto frame (3),

and the interposed multiple tilting wedge' (8), the thread part of whichis effectively protected from grit or splashing water and 'dirt 'by thismeans.V Brackets V(10) and (12) help take away the thrust on the hingesfrom the upper half of the table. A block 4 (13) nailed on the upperforward corner of the table keeps sand and water from dropping on thetilting adjustment parts.

-Flexible supports (14) preferably made .of hickory or locust. wood,support/the Shak.i

ing frame (3) with the attached top (1) in A substantially horizontalmovable position. The supports V`(14e) have a thin center portion (15)and club feet ends (16) and (17), four of the ends (16) continuingupwards for some distance and formingv the before mentioned hinge memberThe ends (16) are keyed solidly to brackets or recesses (18),l attachedto frame (3) and also bolted to frame (3).v The 'ends (17 are similarlykeyedand bolted to recesses in the stringers (19) of the floor frame.

[This forms a flexible support, allowing the table to reciprocate in ahorizontal direction, without any joints to oil or wear out, and at thesame time, when properly proportioned, lthe llexible supports, togetherwith the weight attached thereto, form an inverted cycloidal pendulum,which when set in motion will oscillate in the time and to the distancedesired. When I refer to the supports 14 as being flexible I wish it tobe understood as meaning that said supports are resilient so as` to havea natural rate of vibration similar to the vibrations of a resilientspring Yin order to securethe inverted cycloidal pendulum action abovedescribed.

These supports lmay be made t'o stand at more or less incline; lforroughing work tiltedback as muc-h as 72o from the horizontal, and insuch case, a marked differential movement is obtained without the use ofsprings or bufling means; however, as such a motion'is not horizontal,there is in wet concentration a disturbance of the water which isdetrimental when treating fines and slimes; hence, for best all aroundresults thesupports are only tilted back enough so that on the extremeforward stroke they stand almost vertical and the differential isobtained by other means.

For a reciprocating motion a hollow shaft (20) is clamped fast in theend of frame (3).

Mounted on the shaft (20) is the purposely unbalanced loose pulley (21)and the balanced loose pulley (22), both held 1n position by set collars(24) The unbalanced pulley is provided in any suitable manner withadjustable weights (25) of any desire-d size,

form, or material, of which more or less can frame is a'bumping post(27), in the upper end of which is seated a'soft rubber buffer (28), Arod. (29) having a. small pitch nemesi thread and tail nut (30) at. eachend, adjustably connects the bumping post (2T) below the buffer to thecross beam (3l) of the floor frame. A bracket (32) fastened to the crossbeam (33) of the floor frame, holds up the center of the rod (29)keeping it from vibrating. The stringers (19) are bolted to the crossbeams (22'6), (31) and (33).and this structure forms what I have termedthe floor frame. The cross beams are bolted solidly to a floor orpreferably a foundation. The rod (29), in place of attaching to a crossbeam, may be attached to any rigid point outside of the table structureitself. YVhen the table is reciprocating, the bumping post is drawn upby means of tension rod (29) s o that the center beams (34) of shakingframe (3) touch or strike the rubber buffer (28) more or less hard,according to the kind of motion desired. By this means the motion of thetable is arrested in its'forward Hight, and the loose material restingon the table surface advances. The table also starts back rapidly, dueto the back push of the buffer and the tension set up in the bumpingpost and tension rod b v the bump. @n the forward stroke the start isslow, due to inertia of a body at rest. rfhe total result is adifferential motion, capable of a wide range of adjustment.

Many other arrangements and constructions may be used for this purpose.ln practice ll find, however, that the arrangement illustrated givesuniformly the best all around satisfaction. l also find that the rubberbuffer gives better results than coil springs, which unless properlyconstructed and adjusted.. besides being used in pairs. each spring ofdifferent size. at times will cause synchronous vibration to set in,which never occurs when the construction shown is used.

ln the operation of the table, power is applied by means of a beltindicated at (35). This belt may run in either direction and need notnecessarily be vertical, but can be about 30 out of vertical one way orthe other. lf more than 300. there is some slap tothe belt, which incourse of time would weaken the belt, otherwise the slap of the beltdoes not affect the operation. The stroke of the table being usually gto l, this amount of movement does not affect the running of the belt so4that it can be noticed.

lVhen the belt is shifted to the unbalanced pulley, the tablereciprocates` and the advancing speed of the material being separated isadjusted by drawing up or loosening up on either one of the tail nuts onthe tension rod. `Weight can be added or taken from the unbalancedpulley.

Feed is supplied to the table for about one-third of the length of theupper side of table near head met-ion end. lin case of wet separation,wash water is applied from a boa along the remainder of same side,coming from a pipe located above the wash water box at the upper righthand corner in Fig. l, about where blockl(13) is located. Yhile thematerial moves forward towards the right hand end (see Fig. l), the washwater moves the material down towards the iower side washing the lightermaterial over the riffles and finally over the lower side, while theheavier material is carried by the riflies towards the right hand ordischarge end of the table. the flow of the water so that the edgealways will be keptwet.

Referring to Fig. l, in wet concentration the surface A G F is coveredby practically nothing but water from the incoming feed, which waterruns off over lower side of table from G to F. The surface A B E F iscovered by mostly waste product which runs over the lower side of tablefrom F to E. The surface B D E is covered by the concentrate or heavierportions of the material, and is kicked over the end of the table from Dto E. r)The surface B C D is usually only covered by the wash water ofwhich but very little leaves the table from C to D.

lf a long stroke and gentle motion are required, l. use average amountofcounterweight on p-ulley and ease up on the tension god, lf a short andsharp stroke is required, l use average counterweight and draw up on thetension rod. Long sha-rp stroke is obtained by more counterweight andmore tension. Short gentle stroke is obtained by less counterweight andless tension. As a rulel the c-ounterweight is seldom changed after ithas been found to be large enough, so that the motion is not disarrangedby quite. a large variation in the amount of load, but the strokeadjustment is done by This end is slightly' angular to simply shorteningor lengthening on the tension rod; shortening, which also shortens thestroke, makes the material travel slower; lengthening makes materialtravel faster, with the proviso however that. the tension rod is notlengt-hened to the 'extent that the shaking frame'will hardly touch thebuEer.

The manner here described of supporting a concentrator and impartingdifferential motion to same, forms a combination so simple known camdriven bumping tables in use twenty to forty or more years ago. Themotion itself being a noiseless floating motion, can not be heard atall, and only a gentle dull and barely audible sound is observedwhen thestructure is arrested in its flight by the 'rubber buffer.

The center pieces of the shaking frame continueyin one unbroken lengthfrom the lbuffer to the hollow shaft and take up the inertia of thestructure directly in a horizontal direction from the buffer to the headmotion Without passing through any joints which would be llable to giveout, therebfylf` insuring long life to the shaking frame. he'tension rodin turn brings the shock in almost a horizontal direction back to thefoundation and back of where the table top is supported, thereby Owingto the fact that almost any rate of travel desired can be obtained inthis table,

it is natural .that most operators would em-V ploy al fairly fast rateso as to obtain great capacity; hence this table in outline is madelonger and narrower than is usual in other tables. It also follows thatthe necessity for making short and wide tables for treating slimes,which are hard to move by the usual reciprocating motion, willdisappear, and one type and shape of table will serve the purpose for`all sizes of material, consequently having a universal application.

This invention contains three separate and distinct featureswhich arepreferably, but not necessarily, interdependent.

Thegfirst is a concentrator construction de-v signed to operate on theprinciple of a pendulum. Any slight mechanical assistance made tooperate in the same time as the natural oscillation of the pendulum willoperate it. The table can be operated by a child pushing or pulling4with one hand by simply following up the natural oscillation yof thestructure, giving at each stroke a slight assistance. child operates itwith more ease than a large man, because the large man is barely able tofollow up a motion as fast as re uired in this case.

o illustrate: In the full size commercial machine, which is designed tooperate at 240 strokes per minute, with an average length of stroke of13,/'16', when the table top is removed, `which lowers the center ofgravity thereby shortening the pendulum, the natural number of strokesper minute becomes 380; and a large powerful man can not start the framevibrating, but a small delicate man, especially one who does'no hardwork, has no trouble whatever by pushing or pulling with his thumb andforefinger in starting the frame to vibrate and kee ing it going for along time. When the tab e top is attached to the shaking frame, thecenter of gravity alters and the natural oscillations become 240 perminute and the strong man is able to opcrate it, but not with the sameease as' the smaller man. This proves conclusively that the mechanicalassistancevshould by 'right beat time lwith the pendulum, and when itdoes the power required is but very small. Any mechanical assistancegiven to this pendulum construction and operated in time with it, willproduce similar results.

The second feature is a reciprocating motion produced by a revolvingweight attached to the reciprocating member. The table here describedcan be and has been operated at a greatly different speed from itsnatural vibration, but under thosev conditions it takes correspondinglymore power and more counf.y

the heretofore known head motions, which are, as far as I am aware,stationary. It is the inertia in the revolving unbalanced pulley thatstarts and keeps the structure in motion, and it is the inertia in thependulum structure that makes it possible to drive this at a constantspeed with but only power enough to convey the material being `separatedand overcome the internal friction in the flexible spring supports.

By attaching the means for producing impulse directly to thereciprocating structure and reciprocating with it, I avoid the ham*mering and counter-shock to the structure that has always heretoforeaccompanied the use of bumping blocks in concentrators. Suchcounter-shock is due to the fact that the force giving the impulse hasbeen developed at a fixed point, and not on the reciprocating structureitself.

It is a well known fact that what is known as a bumping table in theart, can make slimes move ahead that cannot be moved by otherreciprocating motions, in spite of the back lash caused by cams or thelike, but the secondary vibration set up by the back lash is detrimentalto saving of slimes. plicants device there is no secondary vibration norback lash, but the material travels on the reciprocating surface withoutthe retrograde movement usually present in other devices used for thesame purpose.

It 'will be observed that the weighted or unbalanced pulley revolves ona relatively stationary shaft instead of a revolving shaft. Consequentlythe bearing bushing in the unbalanced pulleyx any degree wit in limitswithout producing In the aplost motion-or shock. This is due to the factthat no wear'takes place on theside of the bushing where the unbalancein weight is carried but all of the wear takes place on the side of thebushing opposite the location' of v the unbalance in weight, that is, onthe side of the bushing where the reaction occurs. If, however, theunbalanced pulley should be mounted to revolve with a shaft, the latterrevolving in journal bearings, then the action of the unbalance'inweight is to cause lateral movement of the shaft from one side ofits'bearing to the other. This produces wear in the shaft bearing withthe consequent development of lost motion and an undesirable shock whichseriously interferes with, if not destroying, the concentrating action.V Consequentlythe feature of mounting the unbalanced pulley to revolveupon a relatively fixed axle or shaft is an important one inaccomplishing the objects and purthe rtable, as well as the noise andvibraposes of my invention.

Differential motion obtained by cams, etc., in combination with springsor gravity act"- ing against a bumping post, is an old well lmowndevice, and the rapid destruction of tion produced by these devices, areequally well known. This noise and destruction is not present in aStructure embodying my invention, due to the floating, in place of thestationary, means employed and due also to the manner in which lostmotion is automatically eliminated through -the mounting of theunbalanced pulley to revolve upon a relatively fixed axle or shaft andwithout the introduction of any other elements except the forcedeveloped by the unbalanced revolving pulley.

Many variations in the details of'construction and arrangementy would.readily occur to persons skilled in the art and still fall within theSpirit and scope of my invention.

I do not desire, therefore, to' be limited or restrictedl to the exactdetails of construction shown and described, but

Having now set forth the objects and nature of my inventionand aconstruction embodying the principles thereof, what I claim as new anduseful and of my own invention and desire to secureby Letters Patent is:

l. The combination, in a conoentrator, of a horizontally reciprocatingframe, and flexible supportstherefor, a concentrating table hingedlymounted upon said frame, a shaft at. one end of said frame, and anadjusting device at the other, an unbalanced power driven wheel mountedon said shaft, whereby, when said wheel is rotated, a reciprocatingmovement will be transmitted to said frame and table."

2. Thecombination, in a concentrator, of a horizontally reciprocatingframe, and Hexi ble supports therefor, a concentrating table hingedlymountedupon said frame, a shaft on said frame, an unbalanced powerdriven wheel mounted on said shaft for imparting a vibratory movement tosaid frame and table, and means for tensioning said bumper for suddenlyarresting said movement in one direction to a desired degree.,

'3. The combination, ina concentrator, of 4 a horizontally reciprocatingframe, and exible supports therefor, a concentrating taf ble hingedlymounted upon saidr frame, a shaft on said frame, an unbalanced powerdriven wheel mounted on said shaft for imparting a vibratory movementto' said frame and table, and means for suddenly arresting said movementlin one direction toy vshaft to the element, abumper block carried bysaid connections and reciprocating therewith, and a bumper with whichsaid ,block engages.

GUsTAvn A. 'o'vERsTRoMl

